有器件非线性时VSB和COFDM系统性能比较

Comparisons between Performance of VSB and COFDM Systems on the Consideration of Devices Nonlinearity

本文对ＶＳＢ和ＣＯＦＤＭ数字传输系统的性能进行了理论分析和模拟，结果证明从线性系统角度考虑，这两种传输系统在性能上是等价的。本文还就这两种系统对器件非线性的要求进行了分析和模拟，其结果说明ＣＯＦＤＭ系统要求器件具有较小的三阶交调和三阶互调分量，并且，ＣＯＦＤＭ系统峰值－平均功率电平比较大，这将导致ＣＯＦＤＭ接收机中Ａ／Ｄ变换器和数字信号处理位数大于１２比特。

The performances of vestigial sideband (VSB) madulation and coded orthogonal frequency division multiplexing (COFDM) digital transmission systems is analysed and simulated in this paper. The theoretical analysis and simulations prove that these two transmission systems are equivalent on a linear system basis. Both system are compared the existance of device nonlinearity. The simulations prove that the COFDM digital transmission system requires the devices with less third crossmodulation and intermodulation components. Since there is a bigger peakaverage power ratio for the COFDM system,the A/D converter and digital signal processing should have ability of processing more than 12 bits.